1. Field of the Invention
The present invention relates to a magnetic head having a high saturation magnetic flux density, a low coercive force and a low magnetostriction as well as to a method of manufacturing the same.
2. Description of the Related Art
Recently, vigorous research is being performed in an attempt to develop an Fe series film having a saturation magnetic flux density Bs as high as 20 kG. It is known to the art that a Co-rich Fe alloy film is fully comparable with the Fe series film in the value of Bs. Also, the Co-rich Fe alloy film is superior to the Fe series film in its corrosion resistance. Incidentally, the Co-rich Fe alloy usually represents an Fe--Co alloy containing 10 to 40 atm% of Fe with the balance being substantially Co, optionally containing impurity elements. On the other hand, the Fe series film contains at least 85% of Fe together with other impurity elements.
It is necessary for a magnetic film included in a magnetic head to exhibit a low coercive force Hc and a low magnetostriction .lambda.s as well as a high saturation magnetic flux density Bs.
It is reported in "IEEE Trans. Magn., MAG-23 (1987) 2981" that a Co-10%Fe alloy film prepared by plating exhibits a small value of Hc and a small value of .lambda.s, which are fully comparable with those exhibited by an Fe series film.
In the manufacture of various thin films used in a magnetic head, it is desirable to employ a dry process such as sputtering or vapor deposition in place of a wet process, as in the field of semiconductor devices. It should also be noted that, in the case of performing the recording/reproducing operation at a high transfer rate, it is desirable to employ a magnetic film of a multilayer structure including an interposing intermediate insulating layer formed of, for example, silicon dioxide in order to suppress the eddy current generation. It is difficult to manufacture such a magnetic film of a multi-layer structure by means of a wet process such as plating.
Under the circumstances, it is desirable to manufacture a Co-rich Fe alloy film exhibiting still smaller values of Hc and .lambda.s by means of a dry process such as sputtering or vapor deposition. The present inventors have performed vigorous research along this line in an attempt to manufacture a Co-rich Fe alloy film by means of sputtering. It is reported in "J. Appl. Phys., 43 (1972) 3542" that a Co-rich Fe alloy film prepared by sputtering fails to exhibit a low coercive force Hc. However, the present inventors have clarified that a Co-rich Fe alloy film containing about 18% of Fe prepared by sputtering exhibits a small value of Hc, which is fully comparable with that of an alloy film prepared by plating, as reported in "Collection of Lecture Articles in 12th Meeting of Japan Applied Magnetism Institute". However, the Co-18%Fe alloy film prepared by means of sputtering exhibits such a large magnetostriction .lambda.s as 1.times.10.sup.-5 or more. In order to actually use the alloy film in a magnetic head, it is clearly necessary to further lower the value of .lambda.s while maintaining the low value of coercive force Hc.
To reiterate, the Co-rich Fe alloy film prepared nowadays by means of sputtering exhibits such a high saturation magnetic flux density as about 20 kG, but is unsatisfactory in the values of Hc and .lambda.s, making it undesirable to use the alloy film as a magnetic film included in a magnetic head. Naturally, a conventional magnetic head including a Co-rich Fe alloy film prepared by a dry process is incapable of achieving the information recording at a high density.